Abstract
Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) approach for the determination of pesticide residues
A streamlined and effective extraction and cleanup approach for the analysis of diverse pesticide residues un fruits and vegetables has been developed. We are introducing the novel approach as "QuEChERS", which stands for quick, easy, cheap, effective, rugged, and safe. Thje procedure first involves an extraction by votexing 10 g chopped food sample with 10 mL acetonitrile for 1 min in a 40 mL Teflon centrifuge tube. Then, 5 g anhydrous MgSO(4) and 1 g NaCl are added o the extract which is vortexed another minute. This procedure and combination of salts forces a wide range of pesticides to partition into the upper acetonitrile phase. In method development, NMR was used to measure the amount of water in the upper phase, which was correlated with pesticide recoveries to optimize the amount and type of salts to add to the initial extract.Triphenylphosphate (TPP) internal standard is added at this point in the method to provide more accurate and precise results. A 1 mL aliquot of the upper phase is then placed into a 2 mL mini-centrifuge tube and removal of residual water and cleanup are performed simultaneously using a simple procedure that we call "dispersive-SPE". In this case, dispersive-SPE entails vortexing 25 mg primary secondary amines (PSA) sorbent plus 150 mg anhydrous MgSO(4) with the 1 mL extract for 30 s. The PSA does not retain the pesticides, but effectively removes many polar interfering compounds from the food extracts such as organic acids and sugars. The extracts are then centrifuges at high speed for 1 min and the extract is placed into the autosampler vial for analysis.